The present invention relates to the field of flotation devices, and in particular to flotation devices formed of interconnected tubing or pipe and methods of forming the same.
Many prior art float systems exist which use flotation devices formed from one of a variety of conventional materials such as Styrofoam, polyethylene tubs, concrete sections poured around Styrofoam cores and others. Large concrete floats are known in which concrete forms the structural component and the flotation device is enclosed Styrofoam or air.
Flotation devices using interconnected tubing or pipe for buoyancy and methods of forming the same are also generally well-known. U.S. Pat. No. 4,834,014, entitled FLOATING PLATFORM STRUCTURE, issued May 30, 1989, to Olsen, et al., for example, describes a semi-submersible floating platform structure supported by a number of buoyancy bodies in the form of pipes closed at the ends by welded plates. The closed pipes rest in recesses in a plurality of inverted cribs or yokes that also act as buoyancy bodies. A deck structure is mounted on top of columns projected above the buoyancy bodies to form the float structure.
U.S. Pat. No. 6,089,176, entitled APPARATUS FOR AND A METHOD OF CONSTRUCTING A FLOATING DOCK STRUCTURE, issued Jul. 18, 2000, to Costello describes a floating dock structure formed of two sets of parallel and space apart heavy-gauge, high-density polyethylene (HDPE) tubes interconnected and scaled water-tight by a plastic joining process to form a square or rectangular configuration of pontoon floats. An overlying series of deck crosspieces completes the floating dock structure.
Other prior art devices are also known using elongated buoyancy,tubes or pipes with an overlying decking. Such devices as are known in prior art generally connect the elongated buoyancy tubes or pipes transversely between spaced apart generally planar walls.
While useful in some applications, all these prior art devices are generally limited as structural supports.
The present invention provides a structural flotation device and method for producing the same. The structural flotation device of the invention is formed of two elongated shear panels embodied as substantially planar sheets of high-density polyethylene (HDPE) that are spaced apart by two or more substantially parallel and spaced apart heavy-gauge HDPE buoyancy tubes that are transversely oriented relative to the elongated shear panels. All of the buoyancy tubes are of a substantially identical length that is shorter than the elongated shear panels. The openings in both ends of each buoyancy tube are joined to a substantially planar and unbroken surface of each of the elongated shear panels with substantially water-tight structural seams along its entire circumference. The durable HDPE material-based structural flotation device of this invention experiences no electrolysis, requires no painting, and is impervious to destructive marine borers.
Any concrete, wood or other deck can be installed on the top of the floating structure.
This invention is a type of floating structure to be used as a basis for a floating marina or the foundation for any type of floating structure. The flotation units of the structural flotation device of the invention are sections of high-density polyethylene pipe which form the float of any length, but according to one aspect of the invention, the in lengths between about 4 and 12 feet. When the shear panels are straight to form a substantially rectangular floating structure, as shown in the Figures, the ends of the transverse pipe sections are cut square and thermally fused to a pair of shear panels formed by high-density polyethylene (HDPE) sheet material which is slightly wider than the pipe diameter and as long as the entire structural flotation device, which may be any length, but according to one aspect of the invention is about 20 to 40 feet in length. The pipe sections are spaced apart as a function of flotation and structural requirements of the intended application.
According to another aspect of the invention, the floating structure may be curved, as in a round or annular xe2x80x9cdonutxe2x80x9d shape, or angled in another non-rectangular configuration. When the shear panels are curved to form a substantially curved floating structure or angled to form a non-rectangular structure, the ends of the transverse pipe sections are contoured to match the curvature or angularity of the shear panels.
Both the HDPE pipe and HDPE sheet are manufactured products that are commercially available. The currently manufactured sheet are heat fused to form sheet in longer lengths preferred for this invention. Longer lengths may become commercially available in time.
The effectiveness of the flotation system of the invention is the shear strength of the sheet of which the shear panels are formed. When the pipe sections of the buoyancy tubes are connected to the continuous sheet of the shear panels, which span the entire length of the flotation device, the large moment of inertia of the planar sheet results in a flotation device strong enough to operate as a structural device. The rigid connection of the tube sections to the sheet product flotation device maintain the planar orientation of the shear panels to the loaded deck surface such that a rigid structural component results upon which even buildings can be erected. The tube sections range in diameter from between about 14 inches to as much as 48 inches or more, the diameter selected being a function of the amount of flotation required for the application and the expected wave environment.
The effectiveness of the polyethylene sheet welded to the pipe sections also results in the structural flotation device being unusually strong relative to its weight. As a result the structural flotation device of the invention is easier to ship and handle than flotation devices of the prior art and also make very effective sectional barges or floating platforms.
According to another aspect of the invention, the structural flotation device of the invention is alternatively embodied having multiple rows of the transverse HDPE tubes. The vertical depth of the shear panels is increased by use of wider sheets of the HDPE material, thereby making room for the additional rows of transverse tubes. The rows of transverse tubes are either vertically aligned or laterally offset. According to another aspect of the invention, an upper row of the transverse tubes are sealed to create the buoyancy tubes that provide flotation, while one or more of the transverse tubes of the deeper rows are filled with a ballast material to create passive ballast tubes. The passive ballast tubes push the center of gravity of the flotation device lower in the water to provide stability in rough sea conditions.